<div style="background:  rgb(187, 186, 186);margin: 4px;">
  <p style="font-size:14px;">
    这是子组件B、C的内容
    <br>ngOnChanges1：{{data3}}
    <br>ngOnChanges2：{{data4}}
  </p>
  <div style="border: 1px solid red;margin: 5px;font-size:14px">
    <ng-content select=".header"></ng-content>
  </div>
  <div style="border: 1px solid blue;margin: 5px;font-size:14px">
    <ng-content select=".footer"></ng-content>
  </div>
</div>